The acquisition of three-dimensional (3D) point clouds has become an important surveying technique for gathering geospatial information in indoor and outdoor environments. A 3D point cloud may include X, Y, and Z coordinates of a set of points in a 3D coordinate system. These points are often intended to represent the external surfaces of objects. 3D point clouds can be acquired by 3D scanners, stereo vision cameras, time-of-flight lidar systems, and the like.
Thanks to recent improvements in quality and productivity, 3D data are becoming mainstream in many applications, such as urban analysis, building monitoring, industrial modeling, digital terrain generation, forest monitoring, documentation of cultural heritage, among others. Visualizing and inspecting 3D point clouds acquired by 3D scanning devices can be challenging, especially for non-expert users. In order to make these tasks easier, scanning device manufacturers may use photographs to colorize the point clouds. In a colorization process, colors from photographic images are assigned to the corresponding points in a point cloud.